I presume you are selling on platforms similar to Amazon. if yes, please note that the responsibility to report VAT on sales remains with you as a seller and the platforms such as Amazon is merely facilitating the sale between yourself and the customer. The amounts collected by the website/platform is your fund itself which can be withdrawn at your end so the VAT is being collected by you at the end of the day. So all VAT related reporting of sales and obligations remain with you. This is the general scenario with online selling in UAE. So please review your arrangement with the online platform to understand whether you fall within the above general category itself.